The present invention is directed generally to edge card connectors and, more specifically to edge card connectors in which the connector impedance may be controlled by shaping of the connector terminals and in which the connector includes a means for ensuring proper connection with an opposing, mating connector.
High speed data transfer systems require electrical connectors in which the electrical impedance can be controlled in order to maintain the required data transfer rate of the electrical system. It is desirable at high speed data transfer rates to obtain a specific impedance in a connector that matches the impedance of the entire electronic system, i.e., the circuits on a circuit board of an electronic device and either the circuits of opposing electronic device or in a transmission cable. The impedance of a connector may be controlled by the spacing of the terminals, the size of the terminals and the thickness and location of material within the connector housing.
However, low profile connectors, such as those used in SFP (Small Form Factor Pluggable) and SFP-like applications are desired in electronic devices in which space is a premium and thus it is difficult to control the impedance by modifying the spacing and size of the terminals in a reduced-size connector housing. When the terminals are modified, it becomes difficult to retain all of the mechanical functions of the connector, such as terminal retention and engagement while tuning the impedance of the connector. It is also difficult, due to the small size of the SFP-style connectors to provide the connector with some sort of keying function that will ensure proper mating with an opposing mating connector.
The present invention is directed to an improved electrical connector system that combines the aforementioned characteristics and which provides terminals that are capable of accommodating high data transfer speeds of approximately 2 gigabits per second and greater up to and exceeding 10 gigabits per second, and which includes a means for indicating to a user of the system that an opposing, mating connector is properly oriented to mate with the connector.